Electric field controlled systems for contacting liquid phases, especially solvent extraction systems, efficiently create and control mass transfer surface area, and are presently under development in order to replace conventional, mechanically agitated systems. Examples of this development are found in U.S. Pat. No. 4,767,515, entitled "SURFACE AREA GENERATION AND DROPLET SIZE CONTROL IN SOLVENT EXTRACTION SYSTEMS UTILIZING HIGH INTENSITY ELECTRIC FIELDS", and also in U.S. Pat. No. 4,941,959, entitled "ELECTRIC FIELD-DRIVEN, MAGNETICALLY-STABILIZED FERRO-EMULSION PHASE CONTACTOR"; the entire disclosure of each of these U.S. Patents are hereby expressly incorporated herein by reference.
In U.S. Pat. No. 4,767,515, a method and system for solvent extraction is disclosed where droplets are shattered by a high intensity electric field. These shattered droplets form a plurality of smaller droplets which have a greater combined surface area than the original droplet. Dispersion, coalescence and phase separation are accomplished in one vessel through the use of the single pulsing high intensity electric field. Electric field conditions are chosen so that simultaneous dispersion and coalescence are taking place in the emulsion formed in the electric field. The electric field creates a large amount of interfacial surface area for solvent extraction when the droplet is disintegrated and is capable of controlling droplet size and thus droplet stability. These operations take place in the presence of a counter-current flow of the continuous phase.
In U.S. Pat. No. 4,941,959, method and systems for interfacial surface area contact between a dispersed phase liquid and a continuous phase liquid in counter-current flow for purposes such as solvent extraction are disclosed. Initial droplets of a dispersed phase liquid material containing ferromagnetic particles functioning as a "packing" are introduced to a counter-current flow of the continuous phase. A high intensity pulsed electric field is applied so as to shatter the initial droplets into a ferromagnetic emulsion comprising many smaller daughter droplets having a greater combined total surface area than that of the initial droplets in contact with the continuous phase material. A magnetic field is applied to control the position of the ferromagnetic emulsion for enhanced coalescence of the daughter droplets into larger reformed droplets.
These systems, although they exhibit much needed improvements in the subject art, are limited in flow rate by the dropwise introduction of the dispersed phase, and in mixing and mass transfer opportunity by the short, straight flowpath of the dispersed phase through the system. There is a need for electric field controlled systems for contacting liquid phases which do not require complex equipment for effecting the desired process, and which exhibit improvements related to throughput, mixing, and mass transfer opportunity.